1. Field of the Invention
The invention relates to a database management system dealing with multi-media data, and more particularly to a system for managing multi-media data stored in a server, and making use of those multi-media data to supply service to a client in a multi-media data system in a wide-area network such as internet of which world wide web (WWW) is typical.
2. Description of the Related Art
Some of conventional systems dealing with multi-media data select object-oriented approach in order to unify representation of multi-media data having various forms.
For instance, Japanese Unexamined Patent Publication No. 7-200230 published on Aug. 4, 1995, which is based on the U.S. application Ser. No. 168721 filed on Dec. 16, 1993 and assigned to International Business Machines Corporation, has suggested a system in accordance with which it is possible for objects having various interfaces such as image and voice to respond in common message, but in different methods by virtue of object-oriented multi-phase.
FIG. 1 is a block diagram of the suggested system. The illustrated system includes a user input apparatus 1 to which a user gives inputs, a display 2 and an audio output 5 both supply outputs to a user, and a video-output 4 through which image data is displayed on the display 2. The user input apparatus 1, the display, the video-output 4, and the audio output 5 are all electrically connected to a central processing unit (CPU) 3 to thereby be controlled by CPU 3. CPU 3 is also electrically connected to a primary memory unit 6 and a secondary memory unit 7 for storing application programs therein.
Japanese Unexamined Patent Publication No. 3-102573 published on Apr. 26, 1991 has suggested an image processing system for displaying complicated images through the use of object-oriented database. Data of basic image objects is incorporated into complicated image objects, and is associated with a procedure of the basic image objects.
Japanese Unexamined Patent Publication No. 7-182222 has suggested an apparatus for managing an object-oriented database. The suggested apparatus extracts a logical correlation among a plurality of classes represented in object-oriented form, and carries out clustering in accordance with results of extraction.
Japanese Unexamined Patent Publication No. 8-166876 has suggested a method of supporting system development for facilitating system development based on object-oriented analysis design.
One of wide-area networks of which Internet is typical is World Wide Web (hereinafter, referred to simply as "WWW") which is a system for supplying common documents to many and unspecified or specified users. In WWW, a tagged document described with hypertext mark-up language (HTML) is distributed to users through WWW browser which is an application for representation, by making use of a simple communication protocol called HTTP (hypertext transfer protocol). HTML documents are identified by means of a uniform resource locator (URL). By making use of a tag, a link represented with URL may be embedded in a certain HTML document for leading a user to other HTML documents. By tracing such a link, a user can look at a plurality of documents. In these days, URL for images and voices may be designated in HTML document, and hence, images and voices can be regenerated as well as text documents on a screen of WWW browser.
FIG. 2 illustrates one of systems for making use of WWW in multi-media data supply service. The illustrated system is a general system wherein HTTP server operates in association with DB integration system on WWW server machine, and a system for managing a relational database is employed as a back end.
In order to designate data which a user wants to make access, WWW browser 10 transmits URL together with a parameter to HTTP server 20. Then, DB integration system 80 retrieves data from database 90 in accordance with the parameter received in HTTP server 20, and generates HTML document in accordance with a template supplied from a template file 81. The thus generated HTML document is returned to WWW browser 10. Multi-media data such as images 21 and voices 22, and an applet 23 which is a program operable on WWW browser are held as ordinary files. The database 90 manages only names or URL of the files.
In accordance with such conventional systems dealing with multi-media data as mentioned above, all terminals of users have to include a component for transmitting output to and receiving input from a system dealing with multi-media data. Thus, it would be difficult for the conventional systems to distribute multi-media data to many and unspecified users.
This problem can be solved by a system making use of WWW to distribute multi-media data to users, because what is requested to users is just to have a terminal in which some WWW browsers are installed. However, in a conventional system making use of WWW to distribute multi-media data to users, what is stored in a database as data is only letters and figures. Multi-media data is stored in a separate file. Accordingly, as the system becomes larger in a size, it would become quite complicated to manage contents.
In addition, when HTML documents are to be dynamically generated, results of retrieving data from database are merely embedded into HTML documents in the conventional system. If procedures to do are complicated even slightly, script language or programming language has to be used.